The major theme of the play is rebellion and its consequences. The
play concerns the civil strife and political upheaval caused by the
Percies and resulting in war. King Henry IV faces the rebellion
and, with the support of his sons, allies, and royal forces, comes
out victorious.

Minor

Woven with the theme of rebellion is the potentially rebellious
attitude of the common man. Lack of social responsibility is seen
in Falstaff and his gang of robbers and also, early on in the play,
Hal, the king's son. Thus, social strife and disorder are present at
all levels of society.

The theme of honor, of course, underlies the entire play. It is honor
that Hotspur regards as the highest virtue of man and for which he
will undertake his rebellion and ultimately lose his life. The king's
honor is blemished, both through his prior behavior in seizing the
throne and the misbehavior of his son, but is ultimately preserved
as he defeats the forces that threaten the kingdom. Falstaff also
plays upon the theme of honor, both mocking and lacking the trait
himself. For Hal, it will ultimately be honor which drives him to
give up his dissolute life and take his stand at his father's side in
defending the integrity of the kingdom.

Shakespeare is well known for mingling tragic and comic elements
in his plays, and Henry IV is no exception. The main plot is
extremely serious and dire in tone. King Henry IV, the protagonist,
faces civil strife as well as personal problems. He feels a nagging
guilt for having usurped the throne from his predecessor, Richard
II. The Percies, who helped him to power, are now clamoring for
their rewards and threatening rebellion. Worse, his son Hal, the
heir apparent, who should be assisting him in his troubles, seems
more concerned with having fun than with matters of state.

The Elizabethans greatly feared political instability, and rebellion
against the crown was one of the worst imaginable of crimes.
Against this backdrop of foreboding however, Shakespeare has set
much humor and levity. The scenes involving Lady Percy and
Lady Mortimer serve as a foil to the dark deeds their husbands are
about to embark on. The scenes involving Prince Hal and his lowly
companions are delightful, marked by Shakespeare's clever, comic
dialogue, bombastic insults, and brain-twisting puns and word
play. Falstaff, the wittiest character in the play, makes everyone
laugh throughout by his actions and speech. Even at the most dire
moments of battle, Falstaff is present to lighten the mood. Just as
laughter and tears are present in life, so also are humor and gloom
present in equal measures in this play.